Field of the Invention
Embodiments of the present disclosure relate to battery packs for electric tools, which may be detachably mounted to tool main bodies of the electric tools for serving as power sources of the electric tools.
Description of the Related Art
In recent years, battery packs have been used for electric tools and may be detachable mounted to tool main bodies of the electric tools for serving as power sources. In general, a battery pack for an electric tool may include a case serving as an outer casing, and a battery device arranged in the case. The battery device may include a plurality of battery cells capable of charging and discharging, and a circuit board for controlling the charging and discharging operations of the plurality of battery cells. When the charging level of the plurality of battery cells has been reduced, the battery pack may be removed from the tool main body, and may be recharged by a dedicated battery charger. After recharging, the battery pack may be remounted to the tool main body.
The battery pack for an electric tool may generate heat during charging and discharging due to the characteristics of the battery pack as a secondary battery. To this end, a thermistor may be provided in the battery pack for detecting the temperature of the battery cells undergoing charging and discharging (See, for example, Japanese Laid-Open Patent Publication No. 2013-97901). The thermistor may be a linear member. The base end side of the thermistor may be connected to the circuit board. The leading end side of the thermistor may be located between the battery cells arranged in parallel, so that the thermistor is maintained in a state in which it is in contact with the battery cells.
The leading end side of the thermistor may be bonded to the battery cells by using adhesive so that the temperature of the battery cells can be detected in a stable manner. The leading end portion of the thermistor thus bonded to the battery cells can be prevented from being brought out of contact with the battery cells even in the case that the battery cells has moved relative to the circuit board, thus making it possible to detect the temperature of the battery cells in a stable manner.
However, in the case that the leading end portion of the thermistor is bonded to the battery cells by using adhesive as described above, the thermistor may contact the battery cells via the adhesive. This means that the thermistor may indirectly contact the battery cells. Therefore, it may be possible that the thermistor cannot accurately detect the temperature of the battery cells.
Therefore, there has been a need in the art for a technique of enabling a temperature detection device such as a thermistor to accurately detect a temperature of battery cells.